Abdelbaki Benamor

Size and shape controlled of α-Fe2O3 nanoparticles prepared via sol–gel technique and their photocatalytic activity

Haematite (α-Fe2O3) nanoparticles (NPs) of different sizes and morphologies were prepared from two different iron precursors (iron acetate (A) and iron nitrate (N)) using the sol–gel technique, through a reaction with oxalic acid. A pure α-Fe2O3 phase (rhombohedral) that contained particles of different sizes and shapes were obtained from both iron precursors. Transmission electron microscope measurements showed average sizes of 23 ± 2 and 30 ± 2 nm for α-Fe2O3 (A) and α-Fe2O3 (N) formed NPs, respectively. The observed uniform spherical shape for the α-Fe2O3 (A) formed NPs is due to the presence of carboxylic acid (acetic acid) used to control the nucleation and growth process of α-Fe2O3 NPs. However, quasi-spherical particle shapes for α-Fe2O3 (N) were produced in the presence of a mineral acid (nitric acid), which caused the particles to be constrained during their growth step. However, the optical analysis showed that the band gaps of α-Fe2O3 (A) and α-Fe2O3 (N) as 2.63 and 2.60 eV were found, respectively. The surface area results exhibited that both α-Fe2O3 NPs were a porous material with a higher area for α-Fe2O3 (A), which resulted from the uniform shape and smaller size of particles. The magnetic properties were observed to be slightly different for both α-Fe2O3 NPs, which were also attributed to the different particle size of the NPs. Higher photocatalytic activity for congo red dye and 4-chlorophenol degradation under sunlight was achieved by α-Fe2O3 (A), which was attributed to the smaller size and higher surface area compared to α-Fe2O3 (N) NPs.Graphical Abstract

Flocculation and viscoelastic behavior of industrial papermaking suspensions

The effects of the surface charge type and density C496, C492 and A130LMW polyacrylamides (PAMs) on the rheological behavior of real industrial papermaking suspensions were quantitatively related to the degree of flocculation for the same industrial papermaking suspensions. The floc sizes were larger but less dense when anionic PAM was used, and this due to the repulsive forces between the anionic PAM and colloidal particles, leading to the development of open structure flocs of less density. On the other hand, rheological measurements showed that the papermaking suspension is thixotropic with a measurable yield stress. The results showed that the magnitude of the critical stress, τc, complex viscosity, η*, elastic modulus, G′, and viscous modulus, G″, depend on the number of interactions between the PAM chains and particle surface and the strength of those interactions. Cationic PAM showed higher values of η*, G′, G″ and τc compared to anionic PAM. This behavior is in good agreement with Bingham yield stress, τB, adsorption and effective floc density results. Similar to oscillatory measurements, creep measurements also showed that the deformation was much lower for the cationic PAM based suspensions than for the anionic PAM based suspensions. Furthermore, the results revealed that increasing the cationic PAM surface charge decreases the floc size but increases the adsorption rate, elasticity and effective floc density proposing differences in the floc structures, which are not revealed clearly in the Bingham yield stress measurements.

Synthesis and characterization of Sm3+-doped ZnO nanoparticles via a sol–gel method and their photocatalytic application

Spherical ZnO nanoparticles doped by samarium ions were successfully synthesized via a simple sol–gel method. The structures, morphologies, optical properties and surface areas were investigated for all samples using specific characterization methods. The hexagonal wurtzite structure of ZnO and samarium-doped ZnO nanoparticles were determined. The results obtained showed that the sizes of samarium-doped ZnO nanoparticles decreased with increasing samarium ion concentration. It was noticed that in the presence of samarium ions, the band gap slightly changed from the 3.198 eV of ZnO to 3.288 eV for samarium-doped ZnO with enhanced absorption in the UV region. This can be attributed to the transition of electrons from the conduction band to the acceptor energy level of samarium. The XPS results of samarium-doped ZnO, showed that only one oxidation state of samarium, with good incorporation into the ZnO matrix, was presented, with no peak of samarium oxide. The surface areas analyses showed that higher surface areas were obtained for samarium-doped ZnO, which is attributed to the smaller size of the particles. The photocatalytic degradation of 2-chlorophenol was investigated under sunlight in presence of ZnO and samarium-doped ZnO nanoparticles. A higher performance of samarium-doped ZnO for photocatalytic degradation of 2-chlorophenol at 0.50 wt.% was observed, compared to pure ZnO nanoparticles under the same experimental conditions.Graphical abstract

Fuzzy Logic-Based Model to Predict the Impact of Flow Rate and Turbidity on the Performance of Multimedia Filters

AbstractThis paper uses fuzzy logic–based models to predict and evaluate the performance of multimedia filters utilized in wastewater treatment. A fuzzy logic–based model is constructed and trained...

Design philosophy GPC high pressure pilot plant

Abstract The Gas Processing Center (GPC) of Qatar University together with TNO, is building a pilot plant to study reactive absorption of CO 2 from natural gas. This pilot plant will be equipped with state of the art material to test novel high capacity amine solution and gain in depth knowledge under relevant conditions of mass and energy transfer inside absorber and stripper. This pilot plant will be in operation at the GPC in the first quarter 2015.

Membrane Gas Desorption for Natural Gas Treating

Abstract Stable membrane gas desorption (MGD) using a thin-film composite membranes made of hydrophobic glassy polymer poly[1-(trimethylsylil)-1-propyne] on a flexible metal-ceramic microfilter was achieved based on MDEA as CO2-absorption liquid. MGD can be used as a novel methodology for desorption of amine solution for natural gas treatment. In particular, MGD can be useful for obtaining CO2 with methane pipeline specification.

Real-time monitoring of solvent composition for acid gas absorption processes

Abstract Knowledge on the concentrations of active solvent component(s) and absorbed gases are of high importance for acid gas removal processes, such as natural gas processing and CO 2 capture from flue gas. Real-time information of these parameters is currently unavailable. This paper presents recent progress on the development of a promising method that combines in-line measurements with multivariate modelling in order to enable this.